Reciprocating cylinder type compressor having unloading means

ABSTRACT

Unloading means for a reciprocating type compressor, for refrigeration equipment or the like, said means placing the discharge chamber in communication with the suction side of the compressor and including a one-way valve and means for actuating the valve at the proper time. The arrangement is such that the individual cylinders of a multi-cylinder compressor can be independently unloaded as desired.

United States Patent Grant l l Feb. 12, 1974 [54] RECIPROCATING CYLINDERTYPE 1.307.061 6/l9l9 ()lscn 417/440 x COMPRESSOR HAVING UNLOADNG2,036,846 4/1936 Aldingcr 4|7/307 X MEANS FOREIGN PATENTS ()RAPPLICATIONS [75] Inventor: Whitney 1. Grant, Muskego, Wis. 260,1508/1926 lluly 4l7/307 505,027 l2/l954 lt'l 4l7 307 [73] Assignee: VilterManufacturing Corporation, d y

M'lwaukee Primary Examiner-Carlton R. Croyle [22] Filed: Apr. 3, I972Assistant Examiner-Richard Sher [21 1 pp No 240 590 Attorney, Agent, orFirm-James E. Nilles 57 ABSTRACT [52] U.S. Cl. 417/440, 4l7/307 l 1 [51Int. Cl. F04b 49/02 Unloadmg means for a reclprocatmg type compressor ofSearch. for refrigeration equipment or the like, said means 417/275 31placing the discharge chamber in communication with the suction side ofthe compressor and including a [56] References Cited one-way valve andmeans for actuating the valve at the proper time. The arrangement issuch that the in- UNITED STATES PATENTS dividual cylinders of amulti-cylinder compressor can :almen, be independently unloaded asdesired. oung 2,715,992 8/1955 Wilson 417/309 2 Claims, 2 DrawingFigures PAIENIED FEB sum 1 OF 2 RECIPROCATING CYLINDER TYPE COMPRESSORHAVING UNLOADING MEANS BACKGROUND OF THE INVENTION The generalorganization of the compressor C and its This invention pertainsgenerally to refrigeration operation are as follows. The compressorincludes a equipment and more particularly to reciprocating typecompressors having a piston that reciprocates in a cylinder to form anexpansible compression chamber, and the compressor also having a suctionside for the gas, and a high pressure, discharge side. Morespecifically, the invention pertains to unloading means for theindividual compression chambers of such a compressor.

This invention is an improvement over the devices as shown in thefollowing United States patents, all of which have been assigned to anassignee common with the present invention; U.S. Pat. No. 3,540,470issued Nov. 17, 1970 to Schmid and Grant and entitled Diaphragm Valvefor Compressors; U.S. Pat. No. 3,131,856 issued Mar. 5, 1964 to Michenerentitled Reciprocating Piston 'Type Gas Compressor"; U.S. Pat. No.3,490,683, issued Jan. 20, 1970 to Kocher and entitled Gas Compressor;and U.S. Pat. No. 3,261,541 to Kocher issued July 19, 1966 and entitledCompressor Unloading Means.

SUMMARY OF THE INVENTION The present invention provides a reciprocatingtype refrigerant compressor, which compressor is of the type whichincludes a suction chamber, a cylinder and reciprocating piston thereinwhich form a compression chamber. Gas from said suction chamber entersthe compression chamber, is compressed and then is discharged to adischarge outlet. The compressor of the present invention has cylinderunloading means which comprises conduit means that place the compressionchamber in fluid communication with the suction chamber, and thisconduit means has a one-way check valve located closely adjacent thecompression chamber for permitting gas only to leave the compressionchamber, and the conduit means also has an actuatable 1 valve wherebywhen the actuatable valve is open, gas

from said compression chamber can pass through said one-way check valveinto said suction chamber, thereby unloading said compression chamber.

The unloading means mentioned above is located closely adjacent thecompression chamber whereby the volume of gas between the chamber andthe valve is very small, contributing to high efficiency of thecompressor. The arrangement is such that the volume of gas between thecheck valve and the actuatable valve is of no consequence since this gaswill be at discharge pressure because when the actuatable valve isclosed it cannot flow back into the cylinder.

These and other objects and advantages of the present invention willappear hereinafter as this disclosure progresses, reference being had tothe accompanying drawings.

' BRIEF DESCRIPTION OF THE DRAWINGS main housing 1 having a suctionconduit 2 which communicates with a suction chamber 3 at the lowpressure side of the compressor. Gas to be compressed is drawn into thesuction chamber, compressed, and then the high pressure refrigerant gasis charged through the conduit 4 for discharge to a condenser (notshown) or the like of a refrigerant system. The compressor includes anynumber of cylinders 6 in which their respective pistons 7 arereciprocated in suction and compression strokes by the cranks 8 whichare connected to the throws of a crankshaft 9. The crankshaft 9 isjournalled in suitable anti-friction bearings 10 and is driven by apower source (not shown). An oil pump 12 is located at and driven by theend of the crankshaft and acts to supply lubricating fluid such as oilthrough various passages (not shown) and to the various parts of thecompressor in the known manner.

Mounted on the upper end of each of the cylinders is a flat enclosureplate 20 which is urged into sealing relationship with the upper, openend of the cylinder by a relatively strong helical spring 22 actingthrough an annular spring guide 25.

The plates 20 have a series of circumferentially spaced discharge ports23, a plurality of conventional plate diaphragms 24 extend across theports 23 to seal them, so the diaphragm plates can raise within guide 25and thereby permit gas to pass through ports 23 in the conventionalmanner.

Cylinder unloading means are provided for each of the cylinders so thateach can be separately unloaded if desired, as follows. A conduit 30 isin fluid communication with the compression chamber 31 of the cylin'ders and extends through the enclosure plate 20. A one-way check valve,such as the check valve 36 is located in the conduit 30 and closelyadjacent the closure plate 20. The conduit 30 is in communication withanother conduit 31a that leads to the suction chamber 3.

A solenoid operated valve 38 is located in conduit 30 and may beenergized, that is opened, by an automatic means (not shown). A smallconnecting passage 40 is located centrally through the threaded chamber41 which extends through plate 20 and is held captive therein by nuts42. A coupling 43 is threaded on member 41 and contains passage 44 and avalve seat 45 for ball 36.

The passage 40 thus connects the interior of the compression chamber 31with the valve 36 and this passage 40 is sized so that the pressure inthe cylinder never reaches a level high enough to open the dischargevalve 36, which is held closed by the same gas pressure as that whichexists in the discharge chamber.

The valve 36 is located closely adjacent the chamber 31 and its positionis such that flow of gas can only be from the cylinder to the solenoidvalve, and without any retum flow to the chamber 31, and this isimportant to high compressor efficiencies when the compressor is loaded.With the check valve 36 so located, the volume of gas between the top ofthe cylinder and the check valve is a very minimum and approximates thevolume in the connecting passage 40. This volume is considered as a partof the clearance volume; the

smaller the total clearance volume in the compressor, the higher theefficiency.

The volume of gas in the line 30 between the check valve 36 and thesolenoid valve 38 is of no great concern since this gas will be atdischarge pressure when the solenoid valve 38 is closed, and cannot flowback into the cylinder and expand during the suction stroke due to thecheck valve 36.

In the arrangement shown, the conduit 30 is shown connected to the topof the cylinder, but other locatfons and dispositions of the unloadingconduit are of course possible. Because the check valve 36 is located atthe discharge valve assembly in plate 20 and closely adjacent thechamber 31, solenoid valve 38 can be located in any of a variety oflocations in conduit 30, the check valve acting to prevent re-expansionback into the cylinder of the gas that is trapped beyond the checkvalve.

When it is desired to unload the cylinder chamber 31,

the valve 38 is opened and the upward movement of taking place and nogas entering the discharge chamber a during unloading, thereby thecapacity compression is reduced and power is also reduced inapproximately direct proportion to the reduction in capacity.

It will also be noted that a similar unloading conduit a extends fromthe other cylinder shown and has a similar solenoid operated valve 38aand also communicates with the suction chamber 3. Valves 38 and 38a maybe operated independently to unload the cylinders selectively asdesired.

The present unloading arrangement is simple with a minimum number ofrequired parts. Complicated internal unloading mechanism, as for exampleshown in the prior art patent devices previously referred to, have beeneliminated. As a result, wear and replacement of parts and service arereduced to a minimum.

I claim:

1. A reciprocating type, refrigerant compressor of the type having asuction chamber, a cylinder and reciprocating piston which form acompression chamber for receiving low pressure gas from said suctionchamber, and a discharge outlet which receives compressed gas from saidcompression chamber, and cylinder unloading means for said compressorcomprising conduit means between said compression chamber and saidsuction chamber, said conduit means having a one-way check valveaffording substantially unrestrained gas flow from said compressionchamber into a closely adjacent end portion of said conduit means andpreventing return flow of gas from said conduit means into saidcompression chamber; and an actuatable valve downstream from said checkvalve whereby when said actuatable valve is open, gas from saidcompression chamber can pass through said one-way check valve into saidsuction chamber, thereby unloading said compression chamber, saidcompressor including a closure plate mounted across the compressionchamber, and a threadable member extending through said closure plateand having a central passage therein in communication with saidcompression chamber, and wherein said one-way check valve includes acoupling fixed to said threadable member and having a valve seat formedtherein and a shiftable ball in said coupling and abuttable on saidseat.

2. A reciprocating type, refrigerant compressor of the type having asuction chamber, a cylinder and reciprocating piston which form acompression chamber for receiving low pressure gas from said suctionchamber, a closure plate mounted across the compression chamber,resilient means for resiliently biasing said closure plate on saidcylinder, said plate having discharge valve means, and a dischargeoutlet which receives compressed gas from said compression chamber,conduit means extending between said compression chamber and saidsuction chamber, said conduit means including a threadable memberextending through said closure plate and having a central passagetherein, a one-way check valve affording substantially unrestrained gasflow from aportion of said threadable member closely adjacent to saidclosure plate and preventing return flow of gas from said conduit meansinto said compression chamber; said check valve including a couplingfixed to said threadable member and having a valve seat formed thereinand a shiftable ball in said coupling and abuttable on said seat, andsaid conduit means also having a solenoid operated valve downstream fromsaid check valve whereby when said solenoid operated valve is open, gasfrom said compression chamber can pass through said one-way check valveinto said suction chamber, thereby unloading said compression chamber.

1. A reciprocating type, refrigerant compressor of the type having asuction chamber, a cylinder and reciprocating piston which form acompression chamber for receiving low pressure gas from said suctionchamber, and a discharge outlet which receives compressed gas from saidcompression chamber, and cylinder unloading means for said compressorcomprising conduit means between said compression chamber and saidsuction chamber, said conduit means having a one-way check valveaffording substantially unrestrained gas flow from said compressionchamber into a closely adjacent end portion of said conduit means andpreventing return flow of gas from said conduit means into saidcompression chamber; and an actuatable valve downstream from said checkvalve whereby when said actuatable valve is open, gas from saidcompression chamber can pass through said one-way check valve into saidsuction chamber, thereby unloading said compression chamber, saidcompressor including a closure plate mounted across the compressionchamber, and a threadable member extending through said closure plateand having a central passage therein in communication with saidcompression chamber, and wherein said one-way check valve includes acoupling fixed to said threadable member and having a valve seat formedtherein and a shiftable ball in said coupling and abuttable on saidseat.
 2. A reciprocating type, refrigerant compressor of the type havinga suction chamber, a cylinder and reciprocating piston which form acompression chamber for receiving low pressure gas from said suctionchamber, a closure plate mounted across the compression chamber,resilient means for resiliently biasing said closure plate on saidcylinder, said plate having discharge valve means, and a dischargeoutlet which receives compressed gas from said compression chamber,conduit means extending between said compression chamber and saidsuction chamber, said conduit means including a threadable memberextending through said closure plate and having a central passagetherein, a one-way check valve affording substantially unrestrained gasflow from a portion of said threadable member closely adjacent to saidclosure plate and preventing return flow of gas from said conduit meansinto said compression chamber; said check valve including a couplingfixed to said threadablE member and having a valve seat formed thereinand a shiftable ball in said coupling and abuttable on said seat, andsaid conduit means also having a solenoid operated valve downstream fromsaid check valve whereby when said solenoid operated valve is open, gasfrom said compression chamber can pass through said one-way check valveinto said suction chamber, thereby unloading said compression chamber.